Telephone signaling system



Maly l31, 1932. A YW, H, EDWARD-s 1,860,458

TELEPHONE SIGNALING SYSTEM Filed June 15. 1931 Plate Vltage Y INVENTOR WEEdz/UOLZMZS BY ATTORNEY Csi sra'rssl fr rica Pein WILLIAM'IVI. EDWARDS, OF GREAT NECK, '.NEW YORK,KASSIGNOR TO AMERCAN TELE- PHONE AND TELEGRAPH COMPANY, A k(30135190IRIAJION OF NEW YORK K v rnnnrnonn srGNALiNG SYSTEM Application filed June 15,

This: invention yrelates to telephone systems, and more particularly to improvements 1n signaling arrangements for subscribers stations connected to such systems.v

. 5 In the signaling arrangements of the in-A vention there is provided vat the subscribers station a. vacuum tube oscillator Whose circuits are so arranged vthat it Will be energized entirely by the ringing current coin- .10 ing in over the line. The telephone receiver at the Vsubscribers set may beenergized by the oscillator to give the Vaudible signal, or a separatev receiver or loud speaker'vmay be p provided therefor;v Y The arrangements of Y .15 the invention can also be utilized totransmit an audible 'signalrbaclr over the line if de-kV 25 coming ringing current Will Yresult inl re# duced initial cost of the devices and lovver maintenance thereafter. The absence of moving parts other than the receiver diamaintenance.l y

Arrangements have been suggestedlin the past for operating telephone i receivers or loud speakers directly from ringing Current. However, the eiiiciency'of these` elements is low at ringing frequencies and further means are desirable which will givean audible. current of the proper frequency in the receiver.

' One method ofv doinO' this Vhas been to use a vacuumvtube oscillator circuit'employing AV lo and B batteries, which functions when a re1-y lay Controlled bythe ringing current 1s operated.` The use of relays and ofa power supply set for the A and B current is expensive` and also undesirable from Va. maintenance standpoint. The rarrangements of the invention present distinct advantages over the suggestionsfof the prior art in that they provide a frequency changing jdevice which is Y simple in form and Which will operate di-y rectly from the ringing current WithoutV the and volume of the signal than heretofore,

`phragm also tends' to reliability and low n schematically Vand `may ybe connected to theV 1931,. serial. No. 544,605.l

need ofl supplementary battery supply.: Other objects and features of the invention will appeaiimore fully from the detailed description thereof hereinafter given.

In a copending application in the name l' of Edwards, Serial No. 544,604, lfiled June 15, 1931, the 'signaling arrangements of the invention are shown inV connection with party telephone lines. i p v The invention may be more fully understood Yfrom the following description, to-l gether' with the.V accompanying dravviiigain the vFigures 1 tot of which the invention is illustrated. Fig'. 1 is a circuit diagram illustrating ,the inventionschematically. Fig. 2

is a modification of the arrangementsof Fig. il. Figs. 3, 4 and 5 are circuit diagrams showing the applicationy of the invention to sub-` vscribers hand telephone setsyof different types. Fig. Gis acurve'sliovving the operating characteristics of the plate current ofthe oscillators. v have been' utilized tov denote like parts in alljof the figures.

Fig. 1V shows signaling arrangements jfor a lsubscribers station remploying akk vacuum tube oscillator 2 directly energized by the ringing current coming Vin overy the line L. A subscribers telephone set 50 is shown line L. In the line L is a ringing transformer '9. This ringing transformer through its secondary Winding current for Similar reference characters ,supplies the filament of the vacuum tube 2;l The plate voltage is obtained by including the primary ofthe transformer in theplate circuit. A

condenserl isv provided between the line andy the ktransformer primary toprovi'de anopen circuit to .anydirect current'volta-ge applied to the line.. The oscillating circuit shown ing accomplished by the provision vof `the cir'.` cuit'with condenser 5. Ameans of feeding back energy from the vplate circuit to the gridV the audible. signal to the subscriber in re-v.. spouse to the incoming ringing current.'y This may be of the tuned gridv type, the tuning be- Y l f In Fig. 6 the curve A shows the audible fremagnitude.

quency components of the plate current. As alternatingl ringing current is used yto supply the plate voltage, the tube 2 is not operating 'during the time this voltage is ne ative and oscillates at varying degrees o strength while the voltage is positive, as indicated. This results in the production by the receiver 3 of an audible frequency modulated at ringing frequency, which may sound like a warble to the ear.

The circuit arrangements of Fig. 1 may he further utilized to give ank audible ringing signal back to the central office and the calling party. This would be advantageous in that it indicates at the central office or at the calling subscribers set that the station signalng device of the inventionv is functioning, Whereas the ringing signal ordinarily provided for the calling subscriber merely indicates that the ringing circuit at the centraly office is functioning. The transmission back to the calling subscriber of an audible signal is accomplished in the following manner. The

alternating. current in the plate circuit of the oscillator in. returning to the filament finds the primary winding of transformer 9 to be of. high impedance and follows a lower impedance path back to the filament, whichr path comprises ythe line L to the ringing su? plry at the centralv ofiice and condenser l. n this manner an audible signal may be sent to the calling subscriber by the oscillator signaling device of the invention itself.

Fig. 2 isv a modification of the arrangements of Fig;y 1. The arrangements of Fig. 2 der fromA those ofl Fig. l only in. the manner in which the plate voltage of the oscillator tube is obtained. The ringing voltage across the ringing condenser l is used to obtain the plate voltage in this instance rather than the voltage across the primary winding of the transformer 9 in Fig. l.. The arrangements of Fig. 2 will not send an audible signal back to the calling subscriber .as a low impedance' path through the condenser 1 to thel filament is provided for the alternating currents in the. plate circuit. The C. component path is through the ringing machine at the central office. Instances might arise where it would be desirable not to transmit an audible signal back over the line asthese signals might cause cross-talk into adjusting circuits if the currents were of suflicient InY Fig. 3 the arrangementsof the invention are shown as applicable to a subscribers hand telephone set. In this arrangement the telephone receiver 7 of the hand set is utilized as the responsive device to give the signal. T he circuit shown is of thc side tone variety, and the circuit for the transmitter 8 is as follows with the hand set removed' from the hand set mounting: from the line L over conductor 20, through the transmitter 8, contact 1l, conductor 21 to the line L. .A receiver circuit is provided which is as follows: from ther receiver 7 through the transmitter 8, contact l1 conductor 2l, winding of induction coil 6, conductor 22, cont-act 10 to the receiver'7. The incoming currents are transmitted over the transmitter circuit previously traced and transmitted to the receiver circuit through the induction coil 6. Vhen the hand set is on the mounting the talking circuits described above are opened anda circuit in.- cluding a condenser l and a transformer 9 is bridged across the line L. The filament current forV the oscillator 2 is obtained through this transformer. This transformer and condenser are equivalent to a telephone ringer and condenser from the standpoint of ringing frequency impedence. circuit for the oscillator may bc traced as follows: from the plate electrode over conductor 23,v through the receiver 7, over conductor 20,out over one side *of line L and back over the other side of line L, over conductor 24 to the filament. Thus it will be seen that the plate voltage for the tube 2 is obtained by utilizing the ringing voltage across the line L. Accordingly, the signaling device of the invention will transmit back to the calling subscriber an audible signal. Thek grid circuit for the oscillator is as follows: from the grid electrode, over conductor 25, windingvof induction coil 6, over conductor-24 tothe filament. The induction coil G will act as a feed-back coil from the plate The plate circuit to thc grid circuit under these condil tions. The grid circuit may be tuned by the condenser 5 which is connected thereto in a manner similar to that shown in Fig. l. The receiver 7, as has been pointed out, is included in the plate circuit of the oscillator. The induction coil 6 and the receiver 7 are used inboth talking and signaling circuits. 'When the hand set is on the mounting, thc induction coil 6 serves as a feed-back coil and thc receiver. 7 produces the audible signal for the subscriber.l When the hand set is removed, the induction ccil 6 and the receivei` 7 rare connected in the regular talking circuit.

ment.V The plate circuit for the oscillator y2 is as follows: from the plate electrode over conductor 26, through the receiver 7 over conthe art.

ductor 27 to the central office for the pulsating of a component and through the kcondenser l for the a. c. component to the filament. The voltage across thc'condenser l is utilized in this instance to provide the plate voltage and the audible signals are not transmitted back over the line. f Y L In Fig. 5 the arrangements of the invention are shown as applied to an anti-side tone circuit. This type ot circuit is well known in In this modiiication ot the invention the voltage across the ringing condenser l is utilized to obtain tliepplate potential, and the audible signals will not be sent'bacli over the line to the calling subscriber. ln this arrangement the subscribers receiver'? isalso lused to give the audible signal.

While the invention has been disclosed as embodied in certain specific arrangements which are deemed desirable, it isunderstood that it is capable of embodiment in many ot-lier and widely varied forms without de# parting troni the spirit of the invention as defined by the appended claims.

Whatis claimed is: A l 'K l. A line over which signaling currents are being transmitted, a subscribers telef phone set connected to said line, said set in! cluding signaling means comprising a vacuum tube oscillator having its filament and plate circuits so Vconnected to said line that vthe signaling currents transmitted over said line will be utilized as operating currents for said circuits, and an audible responsive devicey connected in the plate circuit ot said oscillator.

2. A telephone `line over which signaling currents are being transmitted, a subscribers telephone set connected to said line, a transformer in said telephone line at said subscribers set, a condenser in series with the primary winding of said transformer, a vacuum tube oscillator ha fing its filament circuit connected to the secondary winding of said transformer, means for completing the plate circuit of the oscillator through said .telephone line to the iilament and in shunt across the condenser and primarywinding of said transformer, and an audible responsive de vice connected in the plate circuit of said oscillator.

` 3. A line over which signaling currents are being transmitted, a subscribers telephone set connected to said line and including a telephone receiver, a vacuum tube oscillator asso,- ciated with said telephone set and having its filament and plate circuits so connected to said line that the .signaling currents transinitted over said line will be utilized :is-open ating currents :tor said circuits, and means for y completing said plate circuit ot said oscillator through said telephone receiver.

, 4. A line over 'whichv signaling lcurrents hone set connected to saidline and includ-` ing a telephone receiver and yan induction coil connection between thetallring circuitl and the receiver circuit, a vacuum tube oscillator associatedvwith said telephone set and having itskiilainent; and-'plate circuits so connected tsaid line that the signaling currents transmitted over ,said line will be utilized as operating currents VJtor said circuits, means Jfor utilizing said induction coil connection as a eed-baclg connection between the plate and grid circuits kolI said oscillatorwhen said subscribers set is not in use, and means-.tor connecting saidsubscribers receiver in said plate circuit ot said oscillator.

5. Aline over which signaling currents are being transmitted, subscriber-s telephone set yconnected tosaidy line, a transformer in said linev at said subscribers set, a condenser in said line between said line and the primary winding of said transformer, a vacuum tubey signaling current across the primary wind-l ing of said transformer will constitute the pla-te circuit potentialv therefor and so that the plate 'circuitgwill be completed fior, its

Vdirect current component through the pri` mary winding of said transformer and Vso that the plate. circuit will be' completed for its alternating current component overv said line, and an audible responsive device connected in the plate circuit of said oscillator.

6. Aline over which signaling currents are being transmitted, a subscribers telephone setconnected to said line, a trans- 'former in said line at said subscribers set, a condenser in said line between said line and the primary winding of said transformer, a

vacuum tube oscillator having its filament circuit connected to the secondary winding of saidtransformeigrmeans for connecting said oscillator to said line so that the voltage drop4 of said signaling current `across said condenser will constitute the plate circuit potential therefor andso that tlieplat-e circuit will be complet-ed for its direct current component over Vsaid line and throughk the pri mary winding of said transformer .and soV that the platek circuit will be coinpletedfor its alternating current component through said condenser, and an audible 'responsive device connected in the plate circuit ot said oscillator.

7. Aline over which signaling current-s are being transmitted, a subscribers telephone set kconnected to said line, a transformer.

having its primary winding bridged across said line at said subscribers set, a condenser in series with said primary winding, a vacuum tube oscillator having its filament circuit connected to the secondary Winding of said transformer, means for connecting said oscillator to said line so that the voltage drop vof said signaling current across said condenser and primary Winding will constitute the plate circuit potential therefor and so that the plate circuit for both its direct current `and alternating current components will be completed over said line, and an audible responsive device in the plate circuit of said oscillator.

, 8. A line over which signaling currents are being transmitted, a Asubscribers telephone set connected to said line, a transformer in said line atsaid subscribers set, a condenser in said line between said line and the primary winding of said transformer, a vacuum tube oscillator having its filament circuit connected to the secondary winding of said transformer, means for connecting said oscillator to said line so that the voltage drop of said signaling current across the primary winding of said transformer will constitute the plate circuit potential therefor, and an audible responsive device connected in the plate circuit of said oscillator.

9. A line over which signaling currents are being transmitted, a subscribers telephone set connected to said line, a transformer in said line at said subscribers set, A

a condenser in said line between said line and the primary Winding of said transformer, a vacuum tube oscillator having its filament circuit connected to the secondary winding yof said transformer, means for connecting said oscillator to said line so that the Voltage drop of said signaling current across said condenser Will constitute the plate circuit potential therefor, and an audible responsive device connected in the plate circuit of said oscillator.

10. A line over which signaling currents are being transmitted, a subscribers telephone set connected to said line, a transformer having its primary Winding bridged across said line at said subscribers set, a condenser in series with said primary Winding, a vacuum tube oscillator having its filament circuit connected to the secondary Winding of said transformer, means for connecting said oscillator to said line so that the voltage dro of said signaling current across said con enser and primary winding will supply the plate circuit potential therefor, and an audible responsive device in the plate circuit of said oscillator.

In testimony whereof, I have signed my name to this specification this 12th day of June 1931.

i WILLIAM I-I. EDWARDS. 

